Jul 132015

Every full Energy Audit should look at Power Factor. It’s funny how often it comes up. Even when you don’t think you have a problem you might in the future.
I first heard about Power Factor Corrections in the late 1980s. My friend’s dad worked for Border States Electric (BSE) as an engineer. He came over to the BSE from Northern States Power (Now Xcel Energy). He was one of the first guys in the area to work on solving this problem using banks of capacitors. He would tell me how electric motors would create a lagging power factor. His job was to calculate the capacitance necessary to correct for low power factors. It didn’t hurt that BSE got a lot of orders for switched capacitor banks.

In the 1990s, my dad and I started to do some energy audits of our own. We would run deal with facilities looking to increase the efficiency of their equipment. It was there they would run afoul of low power factors. Utilities don’t like low power factors and will bill a penalty if your power factor falls below a certain threshold. Our lighting retrofits would have very clean power and high power factors, but because we were using substantially less energy for lighting than before- there was less clean electricity to dilute the dirty (low power factor) electricity, which the motors were using, and hence the facilities would be getting billed a Power Factor penalty. The solution: capacitors and/or new energy efficient motors- but that’s a story for another day.

If you’d like to learn more about Power Factor corrections and motors, I have this article from Moorhead Public Service and their partners at Missouri River Energy Services.

 Posted by at 9:41 am
Oct 282014

It’s hard enough to update the HVAC systems on a older building, but if it is the historical Northrop Auditorium (1929) it is doubly hard. Edward Clements writes about the issues the University of Minnesota faced updating the mechanical and lighting systems this building. In the current issue of Engineered Systems.

“Chilled beam terminal units were also used to provide a thermally comfortable environment while minimizing total system airflow in the back of the house, and a dual-wheel energy recovery AHU (Air Handling Unit) was used to deliver air to the space.”

In addition Clements writes about Displacement Ventilation, Atrium Smoke Control, and Lighting updates. There was a lot work require to reopen by April of 2014.

Northrop Auditorium

Northrop, previously known as Cyrus Northrop Memorial Auditorium, is a stage venue at the University of Minnesota in Minneapolis, Minnesota. -Wikipedia

 Posted by at 12:00 pm
Apr 302014

I have no experience with data centers and ‘Mission Critical’ HVAC systems, but the topic combines three things I’m interested in: Computers, HVAC, and Systems. When I was just a kid I spent a week at Control Data Corp. in Minneapolis. During one of the hottest weeks of the year, my mentor taught me programing. There was no air conditioning at home but in the equipment rooms it was 68 degrees. You almost had to wear a sweater.

Jump forward forty years, and the equipment rooms are jam packed with servers. The cooling load is larger than the equipment load, and they’re cooling 365 days a year, even when it’s -20 degrees outside. Some brave souls are starting to think twice about how they cool their servers. Companies like Google and Facebook have so much invested in their server farms, that any savings translate into millions of dollars.

Kevin Dickens, P.E. in the April 2014 Engineered Systems looks at opencompute.org and their Open Compute Data Center Mechanical Specifications. Open Compute Project is an open source consortium of data centers and equipment manufacturers and interested partners including Facebook. Dickens muses on were all this experimenting has taken us and where it might lead.

For most of us, change has to be incremental. Our risk model does not allow us to step too far outside of our, our management’s, or our client’s comfort zones. But when we can learn from those on the bleeding edge, we should have the courage to step out onto the leading edge. We do that not by stepping out of our comfort zone but by educating ourselves and expanding it instead.

Who doesn’t love a good Psychrometric Chart.

Apr 112014

Thirty years ago I started selling Geothermal Heat Pumps, when I worked at Baker Wholesale in Fargo. We had one customer who was a well driller and he expanded his business into Geothermal. My father helped him design bigger and bigger systems. The bigger the facility the better Geothermal looks. In addition to the greater efficiency, there is also greater flexibility in a multi-zone facility.

In the April 2014 issue of Energy Systems Magazine, Daniel Cohen writes about the Ping Tom Memorial Park Fieldhouse. The field house runs its geothermal heat pumps off of 16) 650-ft-deep vertical wells. This is five times deeper than the well fields we would normally design, but I’m sure they had land use issues so going deep was easier than the drilling more wells.

Ping Tom Memorial Fieldhouse

Chicago’s Ping Tom Memorial Fieldhouse
photo by James Steinkamp/Steinkamp Photography

Environmental Systems Design (ESD) selected Geothermal units for their high energy efficiency ratio (EER) and coefficient of performance (COP). They are estimating a COP of 4 making this heating system 400% more efficient than straight resistant electric heat. In addition they connected modular heat pumps in each zone throughout the field house.

“The heat pumps are independently controlled which allows for energy to be shared and distributed from zone to zone.”

Downsides to Geothermal: it is slightly more expensive to install, but the long term energy profile and operation cost savings makes it the perfect energy source for buildings large and small. Geothermal systems need land to drill the well field, but once it’s in you can use the land for anything you want.

I also like how ESD used CO2 sensors to modulate ventilation airflow based on occupancy. By using VAVs and controlling the ventilation load, the building can retain much of the heat that other buildings vent outside. Add in the Economizer and Energy Recovery system, this building should be inexpensive to operate.

Mar 052014
Spring Point Ledge Light is a sparkplug lighthouse in South Portland, Maine that marks a dangerous obstruction on the west side of the main shipping channel into Portland Harbor. It is now adjacent to the campus of Southern Maine Community College.  The lighthouse was constructed in 1897 by the government after seven steamship companies stated that many of their vessels ran aground on Spring Point Ledge.

Spring Point Ledge Light is a sparkplug lighthouse constructed in 1897, adjacent to the campus of Southern Maine Community College.
photo by Paul VanDerWerf (Flickr)

I’m not sure it’s possible to be further from seawater than in Fargo, North Dakota. That said I found this article by Rob Klinedinst and David Reinheimer, using a Geothermal heat pump with seawater, fascinating. The authors explain why the Southern Maine Community College (SMCC) in South Portland, Maine decided to go with geothermal, and the issues using seawater rather than a closed loop with a glycol solution. I was reminded of my early HVAC years: the first geothermal jobs we work on at Baker Wholesale were open loop systems. We were using Friedrich heat pumps on some large residences, where they had access to active aquifers. This was somewhat rare, so it didn’t take long until we were only designing close loop systems using Command Aire and Econar heat pumps.

The issues using sea water are corrosion and the temperature range of Casco Bay:

Initial roadblocks to using seawater were to find equipment that could efficiently handle the wide temperature ranges in Casco Bay and the corrosiveness of salt water. Only one heat pump model was found with a heating water temperature range of 14°F to 113 ° F, and this was coupled with a system used in the maritime industry — a cupronickel underwater ‘ship-keel cooler’ heat exchanger — that is highly resistant to saltwater corrosion. On ships, the heat exchanger is used to reject heat, but here, it is used to both extract and reject heat from/to the sea.

Rob and David (Harriman’s Higher Education Design Studio) searched the world looking for solutions that would let them take advantage of the sea. They found seawater pumps in Japan, filters and strainers across the country in California, titanium plate-and-frame heat exchanger, and insulated piping systems. All while working with the EPA to get approval. I would have given up before working with the EPA- that could not have been a good experience. The SMCC had a deadline to renovate the Lighthouse Building. The EPA was talking about studies and field testing. HHEDS decide to use a heat exchanger and keep the sea water in the bay.

The cupronickel heat exchangers are located under a nearby dock and positioned three feet below low tide. An uninsulated pipe loops between the heat exchanger and the building. Running the pipes under the ground (an added geothermal source) eliminated the cost of insulated piping. The pipe is filled with 50% food-grade propylene/glycol, with inline pumps moving the liquid at 75 gpm.

Feb 032014

Not only is Fargo cold for six months of the year but once inside the air is dry. I can feel my skin dry up and start to itch. We make sure our humidifiers are working. They’re almost as important as our furnace. But my shins aren’t the only reason to humidify the air. Machines work better, wood doesn’t shrink or crack, and optimal humidity will even keep the doctor away. Gary L. Berlin in the February issue of Engineered Systems, writes on the topic in his article, “Restoring The Low Limit For Indoor Relative Humidity.”

Berlin describes the research history into humidity and health. He covers the what the industry has done to through its ASHRAE established standards to keep humidity at recommended level. And how more work needs to be done to keep indoor relative humidity from falling too low.

See this Sterling Humidity Chart. A decrease in bar width indicates decrease in effect.
Source: ASHRAE, adapted from Sterling et al., 1985.  Lennox.com

Sterling Chart (Optimum relative humidity range to minimize harmful contaminants)

In the early 1980s, Elia Sterling of the University of Vancouver did an extensive study of previously published research concerning indoor relative humidity and its effect on the occupants of an indoor space. This study established that both high and low relative humidity levels had a deleterious and costly effect on the health and productivity of the occupants of a facility as related to bacteria, viruses, fungi, dust mites, respiratory infections, allergies, asthma, and ozone in the workplace, schools, and home.

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Jan 052014

In the new issue of Engineered Systems, Doug Lucht, writes up his experiences troubleshooting an Air Handling Unit at an art museum. He describes the steps he took to locate the problems in an air handling system that never worked properly. The facility had to turn on the chillers as early as March with sub 45-degree temperatures, when the economizers should have been taking care of the building. I love a good mystery and it points out- facilities should not just except poor performance of their equipment but should get to the bottom of it. Solutions were found, Lucht writes…

Once the booster fan was installed, AHU-9 could fully economize. The museum could now keep their chillers off further into the spring and shut them down earlier each fall. They were also able to completely abandon the roof-mounted chiller that served the chilled water fan coil units. Shortly after implementing the solutions, the museum received a check from their utility provider, which made the facility manager look like a hero to the museum curators.

This story also illustrates why cobbling together new and old equipment isn’t always the best way to save money. It demonstrates there are small upgrades that can make big changes to the facility’s comfort and bottom line.

VBA-18 to 190 Ventasen Booster Fan

Ventasen Booster Fan
Product# VBA-18 to 190.

Nov 222011

Recently I fielded a call from an equipment engineer in Minneapolis regarding a HVAC modeling project. He asked about my experience working with ‘Typical Meteorological Year” (TMY) data sets. I’ve modeled a number of Heating, Cooling and Ventilation jobs were I needed the fine detail that TMY data sets provide. I told him the problem I had was using a spreadsheet. I found 8760 lines made for some unwieldy spreadsheets. Instead I put the TMY data in a database and worked my models using a hybrid of database calculations and spreadsheet calculations. He asked where to get the data. It can be found from a number of different sources online. I have been using TMY2 and now TMY3 data sets* from the National Renewable Energy Laboratory (NREL), other sources include…

  • TRY – ASHRAE’s Test Reference Year
  • WYEC – Weather Year for Energy Calculations
  • IWEC – International Weather for Energy Calculations
  • NCDC – National Climatic Data Center
  • TMY – Typical Meteorological Year

According to D.B. Crawley’s paper, “Which weather data should you use for energy simulations of commercial buildings?“, either WYEC nor TMY will work fine. These data sets are pretty good, however you need to keep in mind- they fail at the temperature extremes. The data sets are designed to weed out extreme tempertures in order to create smoother data sets. This can be problematic if you’re also using the simulation to size your equipment. Having said that, these TMY based models will be far more accurately modelling energy usage than using bin hours. They are also better when running what-if scenarios. In order to truly model a building for energy use, particularly where humidity control comes into play it is essential to model the energy use for each hour in a typical year- all 8760 data points.

Detailed hour-by-hour modeling using hourly weather data sets has become commonplace in the evaluation of design alternatives and the design of HVAC systems for larger buildings. For residential and small commercial buildings, calculating design loads based on high and low design temperature is still common practice. The economic issue is when the added cost of the more involved hour-by-hour modeling exercise can be expected to be justified by helping to guide the selection of equipment that provides significantly better part-load performance, resulting in tangible benefits of lower total annual energy cost and better comfort control in the building.-December 2010 ASHRAE Journal.

Other uses of TMY data sets are to adjust set-points based on outdoor temperature to control early morning pre-cooling. Both to take advantage of Lower temperatures and reduced peak demand rates. Building mass can also be used for energy storage. Off-peak heating and night cooling can be based on TMY modeling; shifting HVAC demands to off-peak hours and lower energy rates.

Some of this predictive control is finding its way down to the residential market with smart thermostats. I predict we’ll be seeing more of these smart thermostats… “A trial in 2000 households by Oncor Utilities in Texas resulted in heating and air-conditioning power cuts of 20% to 30% and annual savings up to $400. It also achieved complete AC turnoff at peak hours due to pre-cooling. These examples indicate that approximately 10% of energy to condition buildings can be potentially be saved by the use of control algorithms using forecaster weather conditions.”

*Note: The TMY3s are data sets of hourly values of solar radiation and meteorological elements for a 1-year period. Their intended use is for computer simulations of solar energy conversion systems and building systems to facilitate performance comparisons of different system types, configurations, and locations in the United States and its territories. Because they represent typical rather than extreme conditions, they are not suited for designing systems to meet the worst-case conditions occurring at a location. -NREL

May 172011

Missouri River Energy Services (Moorhead Public Services) has five helpful hints to cut your energy costs in the summer months. I have a couple comments…

#3. Adjust cooling equipment to occupancy schedules.
In the upper midwest this provides larger energy percentage savings due to the narrow spread between the summer design temperature and the indoor temperature.
Unlike the winter where the spread would be 5% in the summer the spread is closer to 25%.*
In the evening this spread narrows more until your cooling equipment doesn’t run at all.
Note: If you are on a Time-of-Day rate, be sure to program your equipment to come back on early enough to take advantage of the lower energy rates.

#4. Upgrade lighting systems.
“Efficient lighting technologies also give off less heat, which reduces the need for air-conditioning.”
This savings is rarely calculated, but it is real and substantial. For commercial buildings. even in our cool climate, we often find cooling equipment running six months or more during the year. By cutting the internal load of your building, not only does your equipment run less, but you can also resize the equipment when it is time to replace it, creating even more savings in upfront equipment costs and maintenance.

* Calculations
(5 degree setback / (70 degree indoor temperature – (-30 Degrees) winter design temperature)) = 5/100 = 5%
(5 degree setback / (90 degree Summer design temperature – 70 degree indoor temperature)) = 5/20 = 25%

May 042011

Bright Energy Solutions (Moorhead Public Service/Missouri River Energy Services) is offering an Excel spreadsheet to help you calculate cost savings and payback potential of lighting retrofits. It can be found under the Lighting New Construction and Lighting Retrofit section of their Energy Calculators For Your Home or Business webpage.

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